Scuba diving opens up a fascinating underwater world, but it also comes with inherent risks if safety guidelines aren’t followed. One of the most well-known diving hazards is decompression sickness, often referred to as “the bends.” But what exactly causes this condition?
When divers descend into the depths, the pressure surrounding them increases significantly. For every 33 feet of descent in seawater, the pressure increases by one atmosphere, or 14.7 pounds per square inch. This pressure change affects the gases we breathe, primarily nitrogen from the air tanks divers use. As pressure increases, more nitrogen dissolves into the diver’s body tissues. The longer and deeper a diver stays underwater, the more nitrogen is absorbed. Unlike oxygen, which the body utilizes, nitrogen is inert and accumulates in tissues over time.
Think of a bottle of carbonated soda as an analogy. The soda is packed with carbon dioxide gas dissolved under pressure. You can’t see the gas initially because it’s in solution. However, when you open the bottle, you release the pressure, and the dissolved gas escapes as bubbles. A similar process occurs in a diver’s body.
During ascent, the surrounding pressure decreases. The nitrogen dissolved in the diver’s tissues now needs to be released as the body can only hold a certain amount of nitrogen at surface pressure. If a diver ascends too rapidly, the excess nitrogen comes out of solution too quickly and forms bubbles in the tissues and bloodstream. These nitrogen bubbles are the primary culprits behind decompression sickness.
These bubbles can cause a range of problems depending on where they form in the body. They can block blood flow, disrupting the oxygen supply to vital organs. They can also stretch or tear blood vessels and nerves, leading to pain and neurological issues. In more severe cases, nitrogen bubbles can trigger blood clots (emboli), blood coagulation, and the release of vasoactive compounds, further exacerbating the condition.
The risk of decompression sickness is directly linked to several factors:
- Depth of the dive: Deeper dives mean greater pressure and more nitrogen absorption.
- Time spent at depth: Longer bottom times lead to increased nitrogen saturation in tissues.
- Ascent rate: Rapid ascents don’t allow enough time for nitrogen to be safely released from the body.
To mitigate these risks, divers rely on dive tables, such as the U.S. Navy Dive Tables, or dive computers. These tools provide guidelines for safe dive depths, bottom times, and ascent rates, minimizing the likelihood of decompression sickness. Understanding the science behind “the bends” is crucial for every diver to ensure safe and enjoyable underwater explorations.
